The radius of each wheel of a car is 16 inches At how many r

The radius of each wheel of a car is 16 inches. At how many revolutions per minute should a spin balancer be set to balance the tires at a speed of 90 miles per hour? Is the setting different for a wheel of radius 14 inches? Is so, what is this setting?

Solution

radius = 16 inches

speed = 90 miles / hours

circumference of wheel = 2*pi* 16 = 32 pi

converting miles / hour to inches / minute

90 / 60 = 1.5 miles / minute

1.5* 5280 feet * 12 inches = 95040 inches / minute

revolutions per minute = 95040 / 32 pi

= 946 revolutions / minute

if radius = 14 inches

revolutiuons per minute = 95040 / 14*2*pi

= 1081 revolutions / minute